Determination of mechanical properties of aged plutonium from ARIES pits by instrumented sharp indentation

We are studying the effects of extended aging in very old weapons-grade plutonium that is being recovered from pits being destroyed for material disposition (MD) purposes. This study is a piggyback study to the demonstration of the Advanced Recovery Integrated Extraction System (ARIES). The plutonium in the weapons selected for ARIES has a unique combination of advanced age and varied service history. The major goal of this study is to determine mechanical properties of aged pit materials. Long-term, safe storage of plutonium from pits depends upon several properties, including the strength and dimensional stability of the metal. A large amount of concrete data about the structure and mechanical properties of plutonium has been accumulated over many years, but very little of this data has a bearing on the properties of the metal as it ages